U.S. Pat. Nos. 4,148,765 and 4,233,432 disclose dicyclopentadiene-modified, unsaturated polyesters. The latter esters have good properties in other respects but are inherently low in tensile strength, percent elongation, impact strength and ductility; this is true also of the polyesteramides disclosed in the above-identified applications. If the several foregoing types of polyesters could be improved in the latter regards, while largely retaining their other properties, this would be highly significant to certain applications--such as, for example, pultrusion-formed, oil well sucker rods.
U.S. Pat. No. 3,297,745 discloses, a homo- and copolymerizable "monomers", certain oligomeric urethane chains capped with vinyl-terminated end groups. A copolymer derived from styrene, an allyloxy-terminated oligomer and a methacryloxy-terminated oligomer is stated to have had higher tensile and flexural moduli than homopolymers of any of the three monomers.
U.S. Pat. No. 4,360,653 discloses impact-resistance polymerizates of the latter types of oligomers with allyl carbonates of polyols.
U.S. Pat. No. 4,390,662 (Ando et al; June 28, 1983; effective reference date Mar. 25, 1981) teaches toughening of polyester and vinyl ester resins (vinyl esters plus styrene) with unsaturated polyurethanes prepared by reacting 1 molecular proportion of an organic diol with from 0.7 to 1 molecular proportion of a diisocyanate and capping the resulting adduct with 2 molecular proportions of a hydroxyalkylacrylate. The Ando polyurethanes have molecular weights corresponding to "weight-average molecular chain extensions, calculated as polystyrene, " of from 100 to 1500.ANG., preferably from 200 to 1000.ANG., most preferably from 300 to 1000.ANG.. That is, the rectilinear length of an unstraightened polystyrene molecule having a molecular weight equal to the weight average molecular weight of the polyurethane is from 100 to 1500.ANG., etc. A length range of from 100 to 1000.ANG. corresponds to a molecular weight range of from about 22,295 to about 2,229,500.
The patent teaches that in order to be an effective toughener, the polyurethane must phase out upon curing of polyester/styrene/urethane compositions (but must not phase out upon curing of vinyl ester/styrene urethane compositions).
Thus, the patent teaches away from the use of oligomeric urethanes for toughening of either polyester or vinyl ester resins. It also teaches away from toughening of polyester resins with urethanes which do not phase out upon curing.